In my experiance most engines are built to run pretty much the same way so think about your car engine in this case. The only time I have ever heard a knocking sound come from a car engine is when the oil was low so you should check to make sure there is enough in your lawn mower.

If it's a loud knock like someone hitting a hammer against steel it is most likely a rod knocking. If you're lucky it could be a bent deck hitting your blade, which can be easily fixed. If it's a rod knock get a new mower.

Could be a few things. first check the oil to ensure its not a valve push rod.could also be a piston push rod and bad bearings and c-clip check to make sure your using the correct spark plug this will cause knocking,change the oil and look for metal shavings and piece's of metal could be rings are bad.

Your lawnmower is making that knocking noise because there is something really wrong with it. You could try and check the engine. You could also check the blades. You might of mowed your lawn too hard growth the lawn mower and it is angry at you. Consider visiting a therapist.

posted by Anonymous
I agree with the ghost thing...look directly at the mower and yell profane things at it, then, tell it if it doesn't work you'll get a new one, and finally, kick it as hard as you can, this should release the demons inside...it works with my wife anyways! add a comment